ANNA UNIVERSITY CHENNAI: CHENNAI – 600 025
B.E DEGREE PROGRAMME :ELECTRONICS AND INSTRUMENTATION ENGINEERING
(Offered in Colleges affiliated to Anna University)
CURRICULUM AND SYLLABUS – REGULATIONS – 2004
SEMESTER IV
EI 1254 ELECTRICAL & ELECTRONIC MEASUREMENTS LAB
AIM
The aim of this lab is to impart the students an adequate knowledge and work experience of the different types of AC and DC bridges, electronic measurement methods for different electronic instruments.
OBJECTIVE
The objective this is, the student acquires sufficient knowledge experience and enhance his capability for handling the equipment and ease of measurement.
Measurement of medium resistance using Wheatstone ‘s bridge.
Kelvin’s Double Bridge.
Calibration of single-phase energy meter.
Calibration of wattmeter.
Schering and Anderson Bridges.
Calibration of ammeter, voltmeter.
Statistical analysis of random errors.
V / I, I / V converters.
CRO Measurements.
Study of transients.P = 45 Total = 45
Detailed Syllabus
1. Measurement Of Medium Resistance Using Wheatstone’s Bridge
Aim
To measure the value of unknown resistance using Wheatstone’s Bridge.
Exercise
Find the value of unknown resistance.
Procedure
Connections are given as per the circuit diagram.
Supply is switched on.
When the unknown resistance s connected, the bridge becomes unbalanced.
The bridge is balanced by varying standard resistance.
The value of unknown resistance is calculated by the given formula.
The above steps are repeated for different value of unknown resistances.
Equipment
Resistors – 1 No
Galvanometer – 1 No
Regulated Power supply – 1 No
Bread board – 1 No
Decade resistance box – 1 No
Multimeter – 1 No
2. Kelvin’s Double Bridge
Aim
To find the unknown value of low resistance using Kelvin’s Double Bridge.
Exercise
Find the unknown value of low resistance.
Procedure
Connections are given as per the circuit diagram.
Supply is switched on.
The bridge becomes unbalanced when unknown resistance R is connected.
The bridge is balanced by varying standard resistance.
Unknown resistance is calculated using balance equation.
The above steps are repeated for various values of unknown resistance.
Equipment
Power supply – 1 No
Fixed resistance – 1 No
Unknown resistors – 1 No
Decade resistance box – 1 No
Multimeter – 1 No
Galvanometer – 1 No
Bred board - 1 No
3. Calibration Of Single Phase Energy Meter
Aim
To calibrate the given energy meter using two substandard wattmeters and to obtain percentage error.
Exercise
Calibrate the given energy meter and draw % error Vs load graph.
Procedure
Connections are given as per the circuit diagram.
The value of load current is adjusted to desire value.
When the red mark on the disk of the energy meter passes the observation point, the stopwatch is started and the number of revolution made by the disc is noted.
The load current is maintained by adjusting the load.
When the disc of the energy meter completes desired number of revolutions the stopwatch is stopped and the time taken is noted.
The procedure is repeated for different values of wattmeter reading and time taken, number of revolutions of the disc is noted down.
The graph is plotted between percentage error and load.
Equipment
1. Wattmeter – 2 No
2. Voltmeter – 1 No
3. Ammeter – 1 No
4. Resistive load – 1 No
4. Calibration Of Wattmeter
Aim
To calibrate the given wattmeter using direct loading.
Exercise
Calibrate the given wattmeter and draw the graph between % error and loadcurrent.
Procedure
Connections are given as per the circuit diagram.
Supply is given at no load condition.
Resistive load is applied in steps and the readings are tabulated.
Graph is drawn between % error and load current.
Equipment
Ammeter – 1 No
Voltmeter – 1 No
Wattmeter – 1 No
4. Load – 1 No
5(a) Schering’s Bridge
Aim
To measure the unknown value of capacitance using Schering’s bridge
Exercise
Measure the unknown value of capacitance.
Procedure
Connections are given as per the circuit.
Supply is witched on.
When unknown value of capacitance is connected, bridge becomes unbalanced.
The bridge is balanced by varying the standard.
The unknown value of capacitance is calculated using the balance equation.
The above steps are repeated for different values of unknown capacitances.
Euipment
1. Resistors - Some set.
2. Capacitors – Some set.
3. Decade Resistance box – 1 No.
4. Decade Capacitance box – 1 No.
5.CRO – 1 No.
6. Function Generator – 1 No.
5(b) Anderson’s Bridge
Aim
To measure the unknown value of inductance using Anderson’s Bridge
Exercise
Measure the unknown value of inductance.
Procedure
1. Connections are given as per the circuit diagram.
2. Supply is switched on.
3. When unknown value of inductance is connected the bridge becomes unbalanced.
4. The unknown value of inductance is calculated by using the balance equation.
5. The above step are repeated for different values of unknown inductance.
Equipment
1. Resistors – Some set
2. Decade Inductance box – 1 No.
3. Decade Condenser box – 1 No.
4. Regulated power supply – 1 No.
5. CRO – 1 No.
6. Bread board - 1 No.
6(a) Calibration of Ammeter
Aim
To calibrate the given ammeter using standard ammeter
Exercise
Calibrate the given ammeter and draw the graph between % error and As.
Procedure
Connections are given as per the circuit diagram.
The standard ammeter should be selected properly.
Supply is switched on.
At no load condition the readings of all the meters are noted.
By gradually increasing the load, the respective readings are taken from the meters.
The readings are tabulated and % error is calculated from the formula.
graph is drawn between As and % error.
The procedure is repeated for both ac and dc supply.
Equipment
Standard ammeter – 1 No.
Ammeter – 1 No.
Variable resistive load – 1 No.
RPS – 1 No.
6(b) Calibration of Voltmeter
Aim
To calibrate the given voltmeter using standard voltmeter.
Exercise
Calibrate the given voltmeter and draw the graph between % error and VS.
Procedure
Connections are given as per the circuit diagram.
The standard voltmeter should be selected properly.
Supply is switched on.
At no load condition the readings of all the meters are noted.
By gradually increasing the voltage, the respective readings are taken from the meters.
The readings are tabulated and % error is calculated from the formula.
Graph is drawn between Vs and % error.
The procedure is repeated for both ac and dc supply.
Equipment
Standard voltmeter – 1 No.
Voltmeter – 1 No.
Auto transformer – 1 No.
RPS – 1 No.
7. Statistical Analysis Of Random Errors
Aim
To analyze the measured data statistically.
Exercise
Take a set of data and calculate the arithmetic mean, deviation from the mean, average deviation, standard deviation and variance.
Procedure
Connect the voltage source to the load.
Measure the load current or load voltage using the digital meter.
After taking the reading switch off the supply.
Switch on the supply and repeat the experiment.
Take 4 readings for same supply voltage or same load current.
Using the data calculate the Arithmetic mean, Deviation from the mean, Average deviation, Standard deviation, Variance.
Equipment
Digital voltmeter or ammeter of suitable range – 1 No
Resistor to act as load – 1 No
Voltage source – 1 No
8. Voltage To Current, Current To Voltage Converter
Aim
To construct a current to voltage & Voltage to current converter circuit.
Exercise
Voltage To Current Converter
Observe the changes in o/p current for changes in i/p voltage.
Connect the circuit
Vary the R.P.S
Observe the O/P current
Current To Voltage Converter
Observe the changes in o/p voltage for changes in i/p current.
Connect the circuit
Vary the i/p current by varying the R.P.S
Tabulate the changes in o/p voltage
Equipment
IC 741 Trainer kit – 1 No
Resistors – A set
RPS – 1 No
Multimeter – 1 No
Ammeter – 1 No
Voltmeter – 1 No
9. CRO Measurements
Aim
To determine the unknown frequency & phase angle using CRO BY Lissajous
pattern.
Exercise
Measure the frequency of a signal.
Measure the Phase angle between any two signals.
Procedure
The function generators are connected in the channels of CRO.
The unknown frequency is applied to Y-plate and known frequency to X-plate.
The known frequency is set to a constant value and unknown frequency is adjusted in multiples or sub multiples of known frequency to get Lissajous pattern.
When the pattern becomes stable, these are graphed, tabulated and analysed.
Equipment
CRO with probes – 1 No.
Function generator – 2 Nos.
Connecting wires
10. Study Of Transients
Aim
Trace the transient waveform and peek time, settling time.
Exercise
Wire up a RLC circuit and obtain its waveform on CRO. Find out peak time,
settling time etc., form the waveform.
Procedure
Wire ups as PLC circuit.
Give a suitable (Sine wave input).
Observe the output waveform storage oscilloscope.
Find out peak line setting time etc, from the waveform.
Equipment
Breadboard – 1 No.
Storage C.R.O. – 1 No.
Resisters – A set.
Capacitors – A set.
Inductors – A set.
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